Hormonal modulation of Toxoplasma gondii infection: Regulation of hormonal receptors and cytokine production in THP-1 cells

Background: Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan able to infect humans and it is common in pregnant women. During pregnancy and lactation, there are changes in the concentration of 17 beta-estradiol (E2), progesterone (Prg), and prolactin (PRL). It is known that a proinflamatory response reduces the susceptibility to be infected, and this response may change according to hormonal impairment. Monocytes and macrophages are the main barrier against many intracellular microorganisms, due to their ability to produce cytokines. The aim of this work was to determine the effect of E2, progesterone, and PRL on the infective capacity of T. gondii, proinflamatory immune response modulation and the expression of hormonal receptors on THP-1 cell stimulated with T. gondii. Methods: The THP-1 cells were infected with 1500 T. gondii tachyzoites, of RH strain. Stimuli were conducted with recombinant PRL (200 ng/mL), E2 (40 nM) y Prg (40 nM). MTT assays were performed to evaluate cellular viability. Western blot assays were carried out to evaluate the expression of the hormonal receptors (PRLR, ER alpha, and ER beta). Cytokines produced were measured with a magnetic bead kit directed to 17 cytokines. Results: Stimuli with E2 and Prg increased T. gondii infection in monocytes after 48 h; however, no differences in infection were observed in PRL stimulus. The E2 decreased the secretion of IL-12 and IL-1 beta and PRL did not modify the production of these cytokines in THP-1 cells stimulated with T. gondii; however, both hormones increased the production of IL-10. Besides, PRL augmented the production of IL-4 and IL-13. In contrast, Prg reduced these cytokines. Our results show that T. gondii induces the expression of ER alpha and ER beta and lowers PRLR. The hormones modify the expression of the receptors of other hormones: Prg decreases PRLR, ER beta and increases ER alpha; E2 diminishes PRLR; and PRL decreases ER alpha and ER beta expression. Conclusion: The hormones can increase T. gondii infection and could be mediating an anti-inflammatory response in THP-1 cells. T. gondii induces changes in the expression of hormonal receptors.